In recent years semiconductor integrated circuits have been highly integrated, and LSI and VLSI have been made and used in actual practices. Along this trend in the art, the minimum line-width of a wiring pattern has been reduced to as small as 0.2 μm or less, the smallest being 0.1 μm or less. To form the wiring pattern fine, the technique of lithography, in which a processing substrate is covered with a resist film, the resist film is selectively exposed and then developed so as to form a resist pattern, the processing substrate is dry etched using the resist pattern as a mask, and then resist pattern is removed to thereby obtain a desired pattern (e.g., a wiring pattern). In this technique of the lithography, a wavelength of exposure light (light used for exposure) is shorten, and moreover the formation of a further fine pattern has been considered by using ionizing radiations such as an electron beam, and X-ray. Especially the lithography technique using ionizing radiations such as an electron beam and X-ray has been positioned as an exposure technique of the following generation, and thus a development of a resist material, which is corresponded to the characteristic of ionizing radiations and has high sensitivity and high resolution, and a method for forming a pattern has been desired.
As the resist material corresponding to the lithography technique using ionizing radiation such as an electron beam or X-ray, there has been a high degree of expectation for a chemically amplified resist containing an acid generator (for example, see U.S. Pat. No. 4,491,628). For example as described in Patent Literature 1, this chemically amplified resist generates acid from a photo acid generator by exposing the same to ultraviolet ray, electron beam, X-ray, or focused ion beam, and the exposed region is changed to an alkali-soluble (positive) or alkali-insoluble (negative) material by baking the resist after exposure and utilizing a catalytic reaction. Accordingly, apparent quantum yield is improved to achieve high sensitivity. Such chemically amplified resist generally contains a base resin, a photo acid generator, various additives and a solvent, and in case of a negative resist, a crosslinking agent is further added.
However, such chemically amplified resist material has insulating properties. Therefore, when exposure is performed with an electron beam, charges are accumulated at the time of the exposure, namely a charge-up phenomenon is caused, and as a result there is a problem such that a position of the formed resist pattern is shifted.
To solve the problem of dislocation of the resist pattern, there has been disclosed a method for preventing the accumulation of charges, in which a conductive resin is coated on a surface of a resist film formed of the chemically amplified resist film to form an antistatic film on the resist film (see Japanese Patent Application Laid-Open (JP-A) Nos. 04-32848 and 08-109351).
However, the conductive resin becomes compatible to a material of a resist film at the time the conductive resin is coated on a surface covered with the resist film, and there are problems such that a pattern is dissolved, or in contrast becomes insoluble at the time of patterning, and the formation of the pattern is failed. Moreover, the scattering of electrons is caused within the antistatic film laminated on the resist film, and thus resolution of the resist pattern is lowered.
The electron beam exposure enables to form fine patterns, but on the other hand, there is a downside that the throughput of the electron beam exposure is significantly inferior to an exposure system using light, because of the drawing method thereof. To compensate this low throughput, a method for carrying out exposure in a light exposure system for a relatively large pattern and carry out exposure using an electron beam for only fine patterns on the identical layer, i.e. an overlay mix and match system, has been proposed.
In the case where the overlay mix and match system is used, it is necessary to use an antistatic film for suppressing the charge-up, with respect to the electron beam exposure. Therefore, as well as the complication of the process, the antistatic film has a large influence to the formation of the resist pattern such as deteriorations of resolution and sensitivity.
Moreover, there has been an attempt to make a constituting material of an antireflection film, which will be paced as an underlying layer of a resist, conductive, and to suppress the charge-up phenomenon without forming an antistatic film (see for example, JP-A No. 2000-191916).
However, in this method, the surface resistance of the antireflection film is as high as 4×107Ω (insufficient conductivity) because a base resin itself does not has conductivity, and thus it is difficult to suppress the charge-up at the time fine patterns are formed.
Accordingly, it is a current situation that a conductive antireflection film which has an excellent antistatic effect as well as suppressing a reflection of ultraviolet ray, and is capable of simply forming a fine resist pattern, wiring pattern, or the like at high resolution and low cost without causing omission or dislocation of the pattern, has not yet provided, and the development of such technology has been desired.